Icositrigonal Number | C # program to find nth Icositrigonal number ; Function to find N - th Icositrigonal number ; Formula to calculate nth Icositrigonal number ; Driver code
using System ; class GFG { static int IcositrigonalNum ( int n ) { return ( 21 * n * n - 19 * n ) / 2 ; } public static void Main ( ) { int n = 3 ; Console . WriteLine ( IcositrigonalNum ( n ) ) ; n = 10 ; Console . WriteLine ( IcositrigonalNum ( n ) ) ; } }